Matthew Whitaker, who was Sessions' chief of staff, is expected to take over oversight of Mueller's investigation into Russian interference in the 2016 election and whether Trump campaign associates colluded with Russia. A source close to the President told CNN that the idea of Whitaker ending or suppressing the Russia probe is not an option as of now.
Trump's dismissal of Sessions has raised yet more questions over how much influence the President will have over Mueller's probe, which has been a source of pain since it began in spring 2017. Trump has complained repeatedly about Mueller's investigation, calling it a "witch hunt," and slammed Sessions in public repeatedly for recusing himself from the Russia probe, a step that helped lead to Deputy Attorney General Rod Rosenstein appointing Mueller.
"It is time for Rosenstein, who is the acting attorney general for the purposes of this investigation, to order Mueller to limit the scope of his investigation to the four corners of the order appointing him special counsel," he wrote then. "If he doesn't, then Mueller's investigation will eventually start to look like a political fishing expedition."
Back in 2017, Whitaker also told CNN's Don Lemon that he could see a scenario where Sessions is replaced with an attorney general who "reduces (Mueller's) budget so low that his investigation grinds to almost a halt."
Trump announced on Twitter Wednesday that Whitaker would fill the role of attorney general while he finds a permanent replacement to be "nominated at a later date."
Sessions recused himself from the Russia investigation after it emerged that he had failed at his Senate confirmation hearing to disclose two pre-election meetings with Russia's ambassador to Washington at a time when Moscow was accused of interfering in the presidential race. The recusal was harshly criticized by Trump and led to the deterioration of their relationship.
Whitaker was a CNN legal commentator and former US attorney who directed the Foundation for Accountability and Civic Trust (FACT), a conservative ethics watchdog group. He ran in the Republican primary for Iowa Senate in 2014.
Whitaker had taken a firm stance against Hillary Clinton while at the group.
He argued in 2016 that "there was a strong case" to bring against Clinton in the FBI's investigation.
"Our judgment is that no reasonable prosecutor would bring such a case," Comey said at a news conference in July 2016.
"I disagree," Whitaker wrote hours after. "I believe myself to have been a reasonable prosecutor, and when the facts and evidence show a criminal violation has been committed, the individuals involved should not dictate whether the case is prosecuted."
Here are other comments Whitaker made on CNN regarding the Mueller investigation:
CNN's Laura Jarrett, Jeremy Herb and Pamela Brown contributed to this report.